Regeneration of Activated Carbon Spent with Phenol and Formation of Hydrogen Peroxide in a Pulsed Discharge Plasma System

Abstract

A pulsed discharge plasma (PDP) system with a multineedle-to-plate geometry electrode was applied in this paper to investigate the regeneration of granular activated carbon (GAC) spent with phenol in the PDP system. Regeneration percentage of the GAC under different conditions of initial solution conductivity and pH values was studied to clarify the regeneration of the GAC by the PDP. Formation of hydrogen peroxide (H2O2) with the same solution conditions was also investigated in this paper. The obtained results show that there was the same changing trend of GAC regeneration and H2O2 formation under different solution conditions, which clarify the critical effect of •OH on the GAC regeneration in the PDP system. The methods of scanning electron microscope (SEM), Brunauer–Emmett–Teller, Boehm titration, and Fourier transform infrared spectroscopy (FTIR) were used in this paper to demonstrate the medication of the GAC by the PDP treatment. The obtained results show that the regenerated GAC could recover a partial pore structure compared with the original GAC by the SEM analysis. The surface area, micropore volume, and total pore volume of the regenerated GAC increased, while the mesopore volume and the macropore volume decreased on the regenerated GAC; comparing with the original GAC, there was higher amount of acidic functional groups and lower amount of basic functional groups on the surface of the regenerated GAC; the intensities of O–H, C=C, C=O, and C–O enhanced significantly by the FTIR analysis.